Latch



Jan. 29, 1946. C. A. wEl'sE y LATCH Filed June 12, 1944 IN1/Emo? Chr] ZJMY@ I Il 4 Patented Jan. 29, 1946 LATCH Carl A. Weise, Los Angeles, Calif., assignor to Douglas Aircraft Company, Inc., Santa Monica,

Calif.

Application June 12, 1944, Serial No. 539,983

12 claims.

The present invention relates to latch mechanism of the type generally used to fasten airplane cowling. Y

Because of the tremendous vibration of the engine and the strong vpressure of the air in advancing the plane at high speeds a great Vstrain is imposed on the cowling and other parts. Sometimes under service conditions, especially when a plane has been subjected to a severe test; the cowling latch has become disengaged allowing the cowling to fall out of place. If this occurs while the plane is traveling at a high rate of speed, the loosened member is either thrown into the propeller disabling it for further use, or itis carried back by the force of the air current and' frequently causes injury to the pilot or damage to the rudder or other control surfaces at the rear of the plane.A A feature which greatly complicates the construction of this part of the plane is that the cowling must be readily demountable for servicing the parts enclosed thereby.

It is therefore an object of the invention to provide a latch that is strong and positive in action such that it will not become loosened by vibration or any other cause whilethe plane is in motion and at the same time is so constructed that it may be easily and quickly manipulated to remove the cowling when it is necessary to service the plane.

A further object of the invention is to provide a design of latch, which, when'closed in locking position, will present no projections which extend beyond' the outer skin of the cowling.

Still another object is to provide a latch which can be operated entirely from the outside of the cowling, automatically engaging the mating part when the operating member is moved, without the necessity of reaching inside the cowling with fingers or tools.

Other objects and advantages of my invention will be apparent to those skilled in the art after a consideration of the following detailed description, taken in conjunction with the accompanying drawing, wherein:

Figure 1 is a top plan view of my improved latch showing it applied to anairplane cowling and with the parts in the process of being connected together;

Figure 2 is a side elevational view of the structure shown in Figure 1 "with the fastening brackets I1 and I8 not shown; and

Figure 3 is a bottom plan view similar to Figure 1 but with the latchmembers disengaged.

Referring now to the drawing, the cowling sections or sheets to be connected together are a pair of horizontally disposed legs I5 and I6 ,e

rigidly related to the body I I and extending perpendicularly inwardly from the wall I2.' The flanges I3 and I4 are secured to bracket plates I1 and I8 respectively which are secured to and extend upwardly from a cowling sheet 5 shown in phantom lines in Figure 1. The leg I6 of the forked portion is detachable from the body I2 Y to facilitate assembly of the parts and the leg I5 may be integrally formed with the body as shown in the drawing. Aligned holes 2| and 22 are provided in the legs I5 and I6 adjacent the forward ends thereof and into these holesv are fitted bushings 23 and 24. 'A double throw crank '26 is provided between the legs I5 and I6. .Crank 26 includes a pair ofvertically spaced arms 21 and 28 which are held in spaced relation byv a bridge 29. .Trunnions 3| and 32 are fixed on the arms 21 and 28 respectively and are journaled in the bushings 23 and 24. y

A latching element in theform of a bar or link 35 is disposed between the spaced arms 21 and 28 of the crank 26 and is pivotally attached vto the arms by a pivot pin 36 which extends through aligned openings in the forward ends of the arms 21 and 28 and the rear enclV of link 35. The latching link 35 extends forwardly and a pair of axially aligned cylindrical lugs or pins 31 and 38 are disposed at itsforward end at opposite sides thereof. The latching link 35 extends beyond the end of cowling sheet 5 and its lugs V 31 and 38 engage an anchorage element in the form of a bifurcated hook 4I fixed on member 9. A spring 56 normally urges the link 35 toward hook 4I.' The hook 4I includes a head 42 having spaced apart side members 42a and a central recess 42h. A threaded shank or stem 43 is formed integral with the head 42 and is adjustably supported in a supporting block 44 which is rigidly secured to a cowling sheet 6. 'I he hook 4I is longitudinally adjustably related to the block 44 by lock nuts 45 and 46 on stem 43 which bear against opposite faces of` the cross wall 44a of block 44.

. on the outer end of the shaft.

vThe shaft 48 extends outwardly beyond the endl` of the trunnion 3| and a hex knob 49 is pinnedY The shaft 48 is normally urged outwardly 'by fa yspring 5I which',

pressed against they spring 63 until it slips off the shoulder 62 permitting the spring 5I to elevate the nut 49 and shaft 48 from locking to release position. The underside of link 35 engages against the stop 64 mounted on the part 5 during the latter portion of the forward movement of link 35 in order to positively raise the link, and retain it in position to clear hook 4`I Whencowling section 6 is`withdrawn, after the -lat'ch has been opened, to kpermit ready access to the engine. When the cowling section 6 is replaced and the hex rod is provided on the shaft 48 between Vth'e outerfend 1'5 of the trunnion 3| and the nut 49. The shaft `48 is restrained from pulling out ofjthe'trunniori 3I by a collar 53 xedon the innerend of the shaft, seating in a recess 54 provided in the trunnion 3 I. d Y The shaft 48 is rotated in a clockwise direction :to engagelink. 3 5 with 1190194' 'and weer@ latch.- ing link 35 inwardly of thegforked I portion of bracket II by means of a wrenchwr4 sir/nilar 'tool applied to the nut'48. v `When the latching link 35 is installe 'locking 'position itis Yslightlyover center. Spring.A 5,6 movesintonengagement lwith camsurface 35a on linkli toward the pivoted end thereof whentheilatching link is Irnovled into fully unlatched positionand serves to maintain it 1in open position. After the latchin'glink 35 has been movediinto locking position, it secured therein by pushing theu hex shaft 48jinwa1j'l, fthe inner end passingV through 'an opening 51 inthe latching-link 35. The shaft 48 `is secured in locking position by a safety catchrdog, 5I which is 'pivotally mounted on the leg I5 and engages over :ashoulder 62 formed on the nut 49 justbelow the flatj sided heX'outer end thereof. The safetycatch '6I' foc `nto lockin ositionb aats rin A. l ls r ed 1 g p `y p g '40"of rotationuof said crank member; anv operat- `63 which is mounted on the leg I5jand contacts Vtheunder side of the catch dog 6I. The bridge 29 abuts and restrains the latching link 35 from continued rotative motion after the Varm has passed 'overicenten i The operation of the latch Vnieczl'iani-srn will be Y "apparent from the aboveA description. .'Startin'g with the parts of the 'mechanism inthe position "shdwnin Figure 3, when the 'cowlin'g sections "are to be connected', the latching link'35 isswung upwardly by rotating the hex nut TI9 'in alcounte'r clockwise directio'na's viewed inFigure 3,` the pivot yp`i113t Aforcing the I right'end of the ylatchin'g link downwardly and forwardly and forcing the cam lug 35d against thesprilgii rocking the free end ofthe link under` the action of `the l"spring updw'ardly into the openingof Ithe h'0okf4I. 'Covn'- -tinued rotation of th'e'inut u49 moves the lugs r3"! *and 38 forward into hooked relation with the 'hook 4I, Thenut 49 is Athen further rotated'to draw the Aarm 35 backinto the l*forked portion-'of latch member `8. When the cowl s'ectir'insl 5 and "6 are drawn tightlytogether, the 'latching link 35 has vpassed'over centery andisfprevented from 'ron rating furiher'py coming iriconiaet Wahine-inner Vface of bridge 29. Theproper relationship of the 'parts to give Vthis/result isfobtainedfby 3adjus'ty Y ment of the nut`s45 and y46 on the threaded shank 43 Yof the hook 4I. The latching 'link L'35fis-"th'e`n, locked in this over-center position by depressing the hexsheii; as througn the opening -sili'n the latching link 35 securing it I'iiepressefd v position bylatchingthesafety:catch 'd giil {over-the' slfiil- 'der 62 on `the fh'exnut '49. Io released-he latch 4 8 is rotated counter-clockwise to again lock the latch, link 35 is moved away from the stop 64 and its free endfr'e-e'nter'sythe hook 4 I This iai-rangement. provides a positive lock for securing the oowlsections in operating position -land one which cannot be jarred open by vibra- Y tion vof the engine or by the strong air pressure to Y means maybe employed inthe practice of the broader'aspects of my invention.

what I'c1aim, therefore, and desire "to secure fgfftfiilctfs@messina :rnhbltdraee mme@ 35 carried byone part and formed'as a bifurcated ingwsp-indleyinountedin a hollwtrunnion of said crank 'and ykeyed thereto to permit A"longitudinal movement of saidspindle but to holdsaid'spindle against rotationaljniovemert `relative vt'o said hol'- lo f trunnion; resilient meanstending to cause 1o giiudiiiai'inovernent'gory-said spindle relativen' V'to said trunniomja'stop formed on said spindle to limit the 1ongitudin'a1 movement thereof; a manually releasable pivoted spring prss'edplate jengagiiigover 9 proiec tion on 'said spindle when vsaid spindle is'd'epr'efsvsed'a'gainst the e'lo'rt 0f said resilient means vwh'ereby'saidspindle 'may beheld nested in 'saidl hollow ttrunnfion "againstfthe effort :of said resilient meansfabrdge piece connecting the of v said double armed "crank V"and 'serving 'afs a stop; a latch 4merr'ibr formed las "a bai; 4arranged between the 'a'riiisj'of' said double 'armed er'aikend rpivoted at one end' onlthe 'crank pin of saidI crank and with its 'f'eeend'formed to provide across iban to 'engage with's'aid "anjch'orage member; ',aiiriiagemet-f'rinedfdroiiiid the periphery. of said -latch member 'its pivoted end'iand 'en 'apertiieforiiied "in said latch member whereby said spindle is preventedfrom longitudinal movement 'in' one direction 'in said hollow trunn'ion untiljsaid Vaperti'i're vhas been brought into `'alignlrnent with 'said hollow trunnion,Vv the arrangementy of parts bein'gsuchthat tionvat which time the "b dge piece'a'rrests furtjherjmoy'efnentl of 4thejfla ch and lcrank, Penabling ich@ lacklljlsilaih in Ql'sd iiqsitinand e'a visual'indicationthat the latchirig mechindle tobejdeprssed into engagement with' anism is properly closed and locked; and a spring acting constantlyto urge the free end of said latch into engagement with the bifurcated hook member except when the latch is in the fully open position.

2. A latching mechanism for securely holding -to-permit longitudinal movement of said spindle but to hold said spindle against rotational movement relatively to said hollow trunnion; resilient means tending to cause longitudinal movement of said spindle relatively to said trunnion; 'a stop formed on said spindle to limit the longitudinal movement thereof; a manually releasable pivotedv spring -pressed plate engaging over a projection on said spindle when said spindle is depressed against the effort of said resilient means, whereby said spindle may be held nested in said hollow trunnion against the effort of saidjresilient means; 4arlatch member formed as a bar arranged between the arms of said'double armed crank and pivoted at one end of the crankpin of said crank and with its free end formed to engage with said anchorage member; an enlargement formedaround the periphery of said latch member at its pivoted end and anv aperture formed in said latch member whereby said spin- 'dle yisprevented from longitudinal movement in one direction in said hollow trunnion until said aperture has been brought/into alignment with said hollow trunnion, the arrangement of parts being such that the pivotal connection of the crank and latch is slightly over center when in fully latched position, enabling the' spindle to be depressed into engagement withthe latch to lock the latch in closed position and to give a visual indication that the latching mechanism is properly closed and locked;` and a spring acting con: stantly to urge the free end of the latch into engagement with said anchorage member except when the latch is in fully open position.

3. A latching mechanism for securely holding a part in 'a desired relation to another part in a structure comprising: an anchorage member carried by one part; a latch housing carried by the other part; a double armed crank member mounted for rotatory movement in said latch housing and having hollow co-axial trunnions' formed on the axis of rotation of said crank mem.- ber; an operating spindle mounted in a hollow trunnion of said crank and keyed thereto to permit longitudinal movement of said spindle but to hold said spindle against rotational movement relatively to said hollow trunnion; resilient means tending to cause longitudinal movement of said spindle relatively to said trunnion; a stop formed on said spindle to limit the longitudinal'movement thereof; a manually releasable pivoted spring pressed plate engaging over a projection on said spindle when said spindle is depressed, whereby said spindle may be held nested in said hollow trunnion against the elort of said resilient means; a latch member formed as a bar arranged between the arms of said double armed crank and pivoted at one end on the crank pin of `said crank and with its free end formed to engage with'said anchorage member; and a spring Y acting constantly to urge th'e free end'ofthe latch into" engagement with said anchorage; member except. when the latch is in fully openjposition.

4. A latching mechanism forsecurely holding a partv in a desired relation to another part in a structure comprising:v an anchorage member car- -ried bygone part; a` latch housingI carriedby ,the

other part; a crank member mounted for rotatory movement kinv said latch housing and having a hollow co-axial trunnionformed on the axis of rotation of said crank member; an `operating spindle mounted in the hollowtrunnion of said crank and keyed thereto to permit longitudinal movement of said spindle but to hold said spindle against Irotational movement relatively to said hollow trunnion; resilient means tending to cause longitudinal movement of said spindle relatively to said trunnion; a stop formed on said spindle to limit the longitudinal. movement thereof; a manually releasable pivoted Vspring pressed plate engaging ,overv a projection on said spindle when rsaid spindle is depressed against the action of said resilient means -whereby said spindle may be held nested in saidhollow trunnion, against the effort of said resilient means; -a latch ,member arranged to lie against said crank and pivoted at one endr on the crank pin of said crank; an enlargement formed around the periphery of said latch member at its pivoted end and an aperture formed in said latch member whereby said spindle is preventgd from longitudinal movement in one direction in said hollow trunnion until said aperture has been brought into alignment with said hollow trunnion, the arrangement of partsv being such that the pivotal connection -ofv the crank and latch is slightly over centerwhen the .partsare in fully latched position, enabling the a part in a desired relation to another part in a structure comprising: an anchorage member carried by one part; a latch housing carried by the other part; a crank member mounted for rotatory movement in said latch housing and having a hollow co-axial trunnion formed on the axis of rotation of said crank member; an operating spindle mounted in the hollow trunnion of said crank and keyed thereto to permit longitudinal movement of said spindle but to hold said spindle against rotational movement relatively to said hollow trunnion; resilient means tending to cause longitudinal movement of said spindle relatively to said trunnion; a stop formed on said spindle to limit the longitudinal movement thereof; a manually releasable pivoted spring pressed plate engaging over a projection on said spindle when said spindle is .depressed against the effort of said resilient means, whereby said spindlemay bei held nested in saidv hollow trunnion against the effort of said resilient means; a latch member formed as a bar pivoted at one end on the crank pin of said crank and with its free end formed to engage with said anchorage member; an enlargement formed around the periphery of said latch memffl ftrunniongthe arrangements of parts `being such 7that'the pivotal connectiondf the rankand latch fs-lightlyoverf'center when `lthe :parts are in `fully laitcifetl position, 'enabling the Spindleto fbe-fde- Fir'e'ss'eel into engagement with @the latcht" ck the latohin closed :position `and :to rgive a 'visual 'hollow 'coaxial trun'n'ion lorme'don `the axis =ci rota-'tion of said member; an operating tsoiridle mounted 1in :the hollow trunnion fof said crank and keyed ltheretoto `p'erriiit longitudinai ario'vementof said spindle butto v.hold #said spindle against rota'tional v'inovenerit relatively lto i'sai'd hollow trunnionrresiiientmeans 'tending to fcause ilong-itudinjal movement yfof^-fsaid 'spindle relatively toisaidltrunnion; alstoprformed'on said spind1e"`to #limit fthesiongitudinai ririovemerit thereof; ra mane -uallyrrereasable member .adapted to engage over :said spindle 'ft/heh fsaidfspindl'e ilis `depres'se'd l-agaihst the effort fof said spring 'whereby .said rsindle"iria'f `beShieldriested in said hollow Etififi'- {1i-ion :against the ieiiortof 'fsaidgresilient meansl; a :1atohi-meinherjoivotedfat fone ehdioh the'crankfpin or isaid cran-k 4arid -with :its free :end iformed to eengage with f'said anchorage member; thear- :rangement 'of ipjarts Lldeing such fthatgthe pivotal connectionfof the 'crankfaiidllatchfis-slightly over reenter when Athe ip'arts are fully latch'ed inosition, enabling the kspindle tjo Vvbe depressed "into feii'ga'gemerit Withlth'e latch 7to lock 'the `latch -in 'clos-edfposition'andtogivegavisualfindioation that r:the `llatcliing mechanism `is A"properly 'closed Vand floked; and resilient rn'eans `-acting t'o urge 'fthe 'lratohitovvardlsaidfanchoragefexceot@whenih open position.

'27. `Latchingl'mean's forise'curelyholdihgfa part 'in a `-desired relation -to another -p'ai'it in-a's'truc'- ture,fsaidriheanecomprising; an anchorage ea-iiifi'ed '1by`ohe fiia'xt; la bracket carried by-the other sa'rt; la'ilatch elfintladalpted t'o f'e'n'gage with vsaid .anchorage fandfmoun'ted l"said lbria'cket for piiifotal movement and-fforfm'ovement fa plane transverse 'toits fpivotal axis toward and away from fsa'id anchorage; #ope ating eans forsai'd latchielenent connected saidieierhehtfdrfsaid :ivotal fniovemen't aridfoarried 4loyg'said bracket 'a d ooniiirisi-ngfa member fmountedrfonrotational movementiand for :movement long-i dinailylo its axis rof i rotation Sand arranged 1in r" e vlongitudinal :position :to fengage isaid element rand :lock it :against said 'to `:and ifrolmovem'ent; means Ifor retaining :said 'operating imean's in sai'dloclifng sposition; 'and resilient fmeans acting fto Turge 'tl'ie latchtowardsaidanchorage:exceptfvirhen inop'en ipcsitin.

t. ihatchingmeans#for securely herding aroart iin fa fdesiredelation `'Lto .another ipart fin 'aistrue- 1titre, :sai'dfnie'ans comprising: fan anchorage vcary friedefby onei part; abracke't carried Jby the'other part :a l,latch elementi adaptedltoiengageewithisaid anchorage and :mounted in :said bracket for ipiv .otal 'movement fand for fmovement lin. ia'pl'an'e transverse -'to =its1-pivotal axis :toward iand away -from i said anchorage; #operating fm-'ean's'f or sai'd latch *elein'ent `"connected -to said latch Aelement Xfor 'ist` id rpivotal vmovement 1 and carried fibylsaid withsaid operating means; resilient means erry 115 fmcvement 1in said llatch housing an'd having fa figagingisaid :latch element to 4maintain said vvelement in 'position to engage said anchorage fmeansexcept when disengaged therefroxnby said 'operating means,V `saidresilient means acting lto Y hold the latch element in disengaged position untilrth'e operating means are again manipulated `tb engage Said anchorage; said loperating means land :latch element being locked together in the ufully latched -positionffbymoving Vsaid member "comprised in the operating )member longitudi- :nally ofthe axis of rotation thereof; and means for retaining :said longitudinally moved :member fin vlocked position vuntil said .means are released. 9. Latching mechanism as set forth in claim 1 andin addition comprising: resilient means acting to hold said latch when freed vfrom said anchorage in position teclear said anchorage until Athe latch operating meansvare again `manipulated to cause the latch V.to engage the anchorage.

`10. Latching means for securely holding a part g iin a closed relation to `another part in a strucifture, rsaid means comprising: .anfanchorage carried-:by one part; a bracket 'carried by the other part; Va latching bar disengageably connected to -said anchorage and mounted on `said bracket'for vmovement away from and toward saidanchorage to lhold'the parts i-n said closed relation or -to-re- :lease them respectively; la rotatable shaft mountfed on said A,bracket for rimparting said `movement ftoisaid :barand connected to said bar :to rilX Isaid bar 1in ,ipositions corresponding to -its Jrotational .fpo'sitions; @a 'plunger slidably Vkeyed to said shaft fand resiliently `held to a limit zposition in Yone direction, and engagea-ble lwith saidban when moved in the 'other direction, to look said `bar against said to and-fro :movement -whensaid' bar is in -said vparts fclosing (position, and .-to impart .rotational movement to i-said shaft. Y

:11. "I iat'ching )means =forsecurely 4but releasably holding ajpart against l-another partina-structure, said means-comprising: an anchorage car- -riedi-by yone fpart; imountin-gmeansV carried by said other Apart; a rotatable element carried .by isaid mounting means alatching bar .pivoted-on said frotatable element; a-bar f-slidably -but `drivingly mounted in :Said :rotatable element and loperable i-byfa vrotative movement to frotatesaid member to fcause said flatching member `to eengage -said anchorage, and A`to vlock l.said -latching `member Yby 'axial fmovement in one direction; resilient means tending 1to;.project said-bar from the position `=in which .it facts to `lock said flatching bar 4intothefposition-in ltvhichfit is'operable :to rotate the `.rotatable .elem'ent; fand fmeans whereby 'said :bar may-beheld against the eiTort of -said resilient means in -position to 1 lockesaid :latching bar.

1&2. 4I atching means for fse'cur'ely ibut :releasably fholding aipartagain's't .another part 'in "a struc- ,tnrersaid means comprising: an anchoragecarried-by=oneipart mounting-means carriedbygsaid fother p'art; a rotatable ielement carried by .said 'mounting' means; a lat'ching :bar :pivoted lon fs'aid .rotatable element; `a bar :slida-bly butjdrivingly fmounted 1in fsaid irotatable :e1-ement Vand fo'perable -b'y avrotative movement :to rotate said `member :to icause isaid latchin'g member ito v:engagersai-d anchorage :and -to llcckrsaid =1atching :memberoby axial movement in one direction; resilient means tending to project said bar from the position in which it acts to lock said latching bar into the position in which it is operable to rotate the rotatable element; means whereby said bar may be held against the effort of said resilient means in position to lock said latching bar; resilient means tending to hold the latching bar in position to enter the anchorage; and a projection on one of the two parts adapted to be held together and positioned to engage against said iatching bar toward the end of its unlatching movement and eieotive to raise and hold the 5 latching member clear of said anchorage against 

